As an instance of the rv_continuous class, burr12 object inherits from it
a collection of generic methods (see below for the full list),
and completes them with details specific for this particular distribution.

This is the PDF corresponding to the twelfth CDF given in Burr’s list;
specifically, it is equation (20) in Burr’s paper [1].

The probability density above is defined in the “standardized” form. To shift
and/or scale the distribution use the loc and scale parameters.
Specifically, burr12.pdf(x,c,d,loc,scale) is identically
equivalent to burr12.pdf(y,c,d)/scale with
y=(x-loc)/scale.

The Burr type 12 distribution is also sometimes referred to as
the Singh-Maddala distribution from NIST [2].